Re: IOError

12 Jun 2003


      On Thursday, 2003-06-12, 21:02, CEST, Dean Herington wrote:
...
On Thu, 12 Jun 2003, Wolfgang Jeltsch wrote:
...
[...] You can then examine t as in the following example:
    t <- try (hGetLine h1)
    case t of
        Left error | isEOFError error
            -> do <EOF handling>
        Right result
            -> do <normal continuation>
Beware: The above causes pattern match failure if a true error (other than
end of file) occurs.  You probably want something like:
case t of
        Left error | isEOFError error
            -> do <EOF handling>
                   | otherwise
            -> do <error handling>
        Right result
            -> do <normal continuation>
Ups, I overlooked this. What I really wanted was:
    case t of
        Left error
            | isEOFError error
                -> do <EOF handling>
            | otherwise
                -> ioError error
        Right result
            -> do <normal continuation>
...
...
[...]
Dean
Wolfgang